Exciton manipulation and transport in 2D semiconductor heterostructure devices

Long-lived interlayer excitons in van der Waals heterostructures based on TMDCs have emerged as a promising platform for realizing solid-state devices based on the electrical control of exciton transport. I will show here how by using van der Waals heterostructures, we can realize excitonic transistors with switching action, confinement and control over diffusion length at room temperature in a reconfigurable potential landscape. Heterostructures with long-wavelength moiré potentials on the other hand, allow addressing local areas of he heterostructure with different local symmetries and optical selection rules. By using externally applied electrical fields, we can control their relative intensities and polarization by different regions in the moiré pattern, characterized by different local symmetries and optical selection rules. Our more advanced excitonic devices with an engineered moiré interaction now also offer the way to manipulate the motion of valley (spin) polarized excitons. By using spatial and time-resolved photoluminescence imaging, we observe the dynamics of exciton transport, enabling a direct estimation of the exciton mobility. The presence of interactions significantly modifies the diffusive transport of excitons, effectively acting as a source of drift force and enhancing the diffusion coefficient by one order of magnitude. The repulsive dipolar interactions combined with the electrical control of interlayer excitons opens up appealing new perspectives for excitonic devices.